whitespace: Use `define-globalized-minor-mode' for global mode

* lisp/whitespace.el (global-whitespace-mode): Fix interoperability
between `whitespace-mode' and `global-whitespace-mode' by using
`define-globalized-minor-mode'.  (Bug#60334)
* test/lisp/whitespace-tests.el (whitespace-tests--global): Add a
regression test.

1 files changed, 18 insertions, 0 deletions

diff --git a/test/lisp/whitespace-tests.el b/test/lisp/whitespace-tests.el
index d72748cd0c9..3a53e025036 100644
--- a/test/lisp/whitespace-tests.el
+++ b/test/lisp/whitespace-tests.el
@@ -57,6 +57,24 @@ buffer's content."
     (whitespace-cleanup)
     (buffer-string)))
 
+(ert-deftest whitespace-tests--global ()
+  (let ((backup global-whitespace-mode)
+        (noninteractive nil)
+        (whitespace-enable-predicate (lambda () t)))
+    (unwind-protect
+        (progn
+          (global-whitespace-mode 1)
+          (ert-with-test-buffer-selected ()
+            (normal-mode)
+            (should whitespace-mode)
+            (global-whitespace-mode -1)
+            (should (null whitespace-mode))
+            (whitespace-mode 1)
+            (should whitespace-mode)
+            (global-whitespace-mode 1)
+            (should whitespace-mode)))
+      (global-whitespace-mode (if backup 1 -1)))))
+
 (ert-deftest whitespace-cleanup-eob ()
   (let ((whitespace-style '(empty)))
     (should (equal (whitespace-tests--cleanup-string "a\n")